共查询到20条相似文献，搜索用时 15 毫秒
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Taeseup Song ;Hyungkyu Han ;Heechae Choi ;Jung Woo Lee ;Hyunjung Park ;Sangkyu Lee ;Won II Park ;Seungchul Kim ;Li Liu ;Ungyu Paik 《Nano Research》2014,(4):491-501
The inherently low electrical conductivity of TiO2-based electrodes as well as the high electrical resistance between an electrode and a current collector represents a major obstacle to their use as an anode for lithium ion batteries. In this study, we report on high-density TiO2 nanotubes （NTs） branched onto a carbon nanofiber （CNF） ＂tree＂ that provide a low resistance current path between the current collector and the TiO2 NTs. Compared to a TiO2 NT array grown directly on the current collector, the branched TiO2 NTs tree, coupled with the CNF electrode, exhibited -10 times higher areal energy density and excellent rate capability （discharge capacity of -150 mA.h.g-1 at a current density of 1,000 mA·g-1）. Based on the detailed experimental results and associated theoretical analysis, we demonstrate that the introduction of CNFs with direct electric contact with the current collector enables a significant increase in areal capacity （mA·h·cm-2） as well as excellent rate capability. 相似文献
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Yaru Liang Xiang Xiong Zhuijun Xu Qingbing Xia Liyang Wan Rutie Liu Guoxin Chen Shu‐Lei Chou 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(26)
Lithium‐ion batteries (LIBs) have been widely applied and studied as an effective energy supplement for a variety of electronic devices. Titanium dioxide (TiO2), with a high theoretical capacity (335 mAh g?1) and low volume expansion ratio upon lithiation, has been considered as one of the most promising anode materials for LIBs. However, the application of TiO2 is hindered by its low electrical conductivity and slow ionic diffusion rate. Herein, a 2D ultrathin mesoporous TiO2/reduced graphene (rGO) heterostructure is fabricated via a layer‐by‐layer assembly process. The synergistic effect of ultrathin mesoporous TiO2 and the rGO nanosheets significantly enhances the ionic diffusion and electron conductivity of the composite. The introduced 2D mesoporous heterostructure delivers a significantly improved capacity of 350 mAh g?1 at a current density of 200 mA g?1 and excellent cycling stability, with a capacity of 245 mAh g?1 maintained over 1000 cycles at a high current density of 1 A g?1. The in situ transmission electron microscopy analysis indicates that the volume of the as‐prepared 2D heterostructures changes slightly upon the insertion and extraction of Li+, thus contributing to the enhanced long‐cycle performance. 相似文献
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Ge Chen Min Li Fan Li Shaorui Sun Dingguo Xia 《Advanced materials (Deerfield Beach, Fla.)》2010,22(11):1258-1262
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层状锂锰氧化物作为锂离子电池的正极材料，具有无毒、低成本、能量密度高等优点。综述了近年来锂离子电池层状正极材料的研究进展，主要讨论了层状锂锰氧化物掺杂改性对其结构和电化学性能的影响，以及多元复合材料LiMnxCoyNi1-x-yO2的结构特性、制备方法、各金属元素含量的变化对其电性能的影响。 相似文献
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Liu H Bi Z Sun XG Unocic RR Paranthaman MP Dai S Brown GM 《Advanced materials (Deerfield Beach, Fla.)》2011,23(30):3450-3454
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Surface engineering of electrode materials to yield favorable electrochemical performance is a hot spot of current research in the energy storage area. Here, this Report highlights recent progress in rational surface engineering strategies in association with their effects on the electrochemical properties. The electrochemical performance enhancement due to both intrinsic nanostructuring and hybridization with surface functional species is elaborated. The focus here is lithium and sodium ion batteries, but the discussed surface engineering strategies may also apply to electrodes of other emergent devices such as metal‐sulfur and metal‐oxygen batteries. 相似文献
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Huiteng Tan Lianhua Xu Hongbo Geng Xianhong Rui Chengchao Li Shaoming Huang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(21)
To further increase the energy and power densities of lithium‐ion batteries (LIBs), monoclinic Li3V2(PO4)3 attracts much attention. However, the intrinsic low electrical conductivity (2.4 × 10?7 S cm?1) and sluggish kinetics become major drawbacks that keep Li3V2(PO4)3 away from meeting its full potential in high rate performance. Recently, significant breakthroughs in electrochemical performance (e.g., rate capability and cycling stability) have been achieved by utilizing advanced nanotechnologies. The nanostructured Li3V2(PO4)3 hybrid cathodes not only improve the electrical conductivity, but also provide high electrode/electrolyte contact interfaces, favorable electron and Li+ transport properties, and good accommodation of strain upon Li+ insertion/extraction. In this Review, light is shed on recent developments in the application of 0D (nanoparticles), 1D (nanowires and nanobelts), 2D (nanoplates and nanosheets), and 3D (nanospheres) Li3V2(PO4)3 for high‐performance LIBs, especially highlighting their synthetic strategies and promising electrochemical properties. Finally, the future prospects of nanostructured Li3V2(PO4)3 cathodes are discussed. 相似文献
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以两种糖类化合物(葡萄糖与水溶性淀粉)为碳源,以SnCl4.5H2O为锡源用一步水热法制备了SnO2@C复合物。使用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、N2吸脱附法和透射电镜(TEM)表征其组成和微观结构,并采用恒电流充放电测试、循环伏安法(CV)和电化学阻抗谱(EIS)表征其作为锂离子电池负极材料的电化学性能。结果表明,糖类前驱体衍生的热解炭和直径为4~5 nm的SnO2纳米点生成了稳定的复合结构,炭基体的缓冲作用和材料纳米化缓解了SnO2的体积膨胀效应,使材料的结构稳定性和电化学性能提高。由于葡萄糖热解炭的有序度比淀粉热解炭更高,这组试样具有更好的循环性能和倍率性能,在2 A/g大电流密度下其比容量高于400 mAh/g。 相似文献
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Song Chen Zhuo Chen Xingyan Xu Chuanbao Cao Min Xia Yunjun Luo 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(12)
Constructing unique mesoporous 2D Si nanostructures to shorten the lithium‐ion diffusion pathway, facilitate interfacial charge transfer, and enlarge the electrode–electrolyte interface offers exciting opportunities in future high‐performance lithium‐ion batteries. However, simultaneous realization of 2D and mesoporous structures for Si material is quite difficult due to its non‐van der Waals structure. Here, the coexistence of both mesoporous and 2D ultrathin nanosheets in the Si anodes and considerably high surface area (381.6 m2 g?1) are successfully achieved by a scalable and cost‐efficient method. After being encapsulated with the homogeneous carbon layer, the Si/C nanocomposite anodes achieve outstanding reversible capacity, high cycle stability, and excellent rate capability. In particular, the reversible capacity reaches 1072.2 mA h g?1 at 4 A g?1 even after 500 cycles. The obvious enhancements can be attributed to the synergistic effect between the unique 2D mesoporous nanostructure and carbon capsulation. Furthermore, full‐cell evaluations indicate that the unique Si/C nanostructures have a great potential in the next‐generation lithium‐ion battery. These findings not only greatly improve the electrochemical performances of Si anode, but also shine some light on designing the unique nanomaterials for various energy devices. 相似文献
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Xin Zhang;Tao Wu;Jiyuan Jian;Shuang Lin;Dandan Sun;Gang Fu;Yan Xu;Ziwei Liu;Sai Li;Hua Huo;Yulin Ma;Geping Yin;Pengjian Zuo;Xinqun Cheng;Chunyu Du; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(45):2404488
A great challenge in the commercialization process of layered Ni-rich cathode material LiNixCoyMn1-x-yO2 (NCM, x ≥ 80%) for lithium-ion batteries is the surface instability, which is exacerbated by the increase in nickel content. The high surface alkalinity and unavoidable cathode/electrolyte interface side reactions result in significant decrease for the capacity of NCM material. Surface coating and doping are common and effective ways to improve the electrochemical performance of Ni-rich cathode material. In this study, an in situ reaction is induced on the surface of secondary particles of NCM material to construct a stable lithium sulfate coating, while achieving sulfur doping in the near surface region. The synergistic modification of lithium sulfate coating and lattice sulfur doping significantly reduced the content of harmful residual lithium compounds (RLCs) on the surface of NCM material, suppressed the side reactions between the cathode material surface and electrolyte and the degradation of surface structure of the NCM material, effectively improved the rate capability and cycling stability of the NCM material. 相似文献
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《Small Methods》2017,1(3)
As state‐of‐the‐art rechargeable energy‐storage devices, lithium‐ion batteries (LIBs) are widely applied in various areas, such as storage of electrical energy converted from renewable energy and powering portable electronic devices and electric vehicles (EVs). Nevertheless, the energy density and working life of current commercial LIBs cannot satisfy the rapid development of these applications. It is urgently required that the electrochemical performance of LIBs, which is mainly determined by the electroactive electrode materials, is improved. However, commercial graphite‐based anode materials deliver a relatively low theoretical capacity of 372 mA h g−1, severely hindering the increase of the energy density of LIBs. Recently, M‐based anode (M represents Si, Ge, and Sn) materials have attracted great attention due to their high theoretical capacity and reasonable anodic voltage. However, the application of M‐based anode materials is seriously limited by a series of several critical problems, such as poor kinetics and huge volume change on cycling. Here, these fundamental problems leading to poor electrochemical performance are discussed, and a series of reasonable nanostructures for M‐based anodes with improved electrochemical performance is summarized, demonstrating that the dimensional control in structure design plays a critical role for solving these problems. 相似文献